<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        #box{
            width: 500px;
            height: 100px;
            border: 2px solid rosybrown;
        }
    </style>
    <script type="text/javascript">
      
        
        function start(){     
            var text = document.getElementById("in").value;
            var div = document.getElementById("box");
            div.innerHTML = text;
        }
    
    </script>
</head>
<body>
    <input id="in" type="text" >&nbsp;
    <button onclick="start()">复制</button>


    <div id="box">    
    </div>
   
</body>
</html>